How do the number of valence electrons an element has change from column to column?

Increases by an unit.          

Explanation:

The periodic table refers to the table in which the chemical elements are arrangement in the increasing order of their atomic number (Z). This table contains 18 vertical columns, known as groups and 7 horizontal rows, called columns.

As we move across the period, i.e. left to right from one column to another; the number of valence electrons in the valence shell of a chemical element progressively increases by an unit.

explanation:

crosscutting concepts have application across all domains of science. as such, they are a way of linking the different domains of science. they include patterns; cause and effect; scale, proportion, and quantity; systems and system models; energy and matter; structure and function; and stability and change.

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.